Background: Psychotic and mixed affective episodes are prevalent in the course of bipolar disorder. Despite many studies on the implications of psychotic mania (PM), psychotic depression (PD) and mixed affective episodes (MAE), relatively little is known about the relationship between the three subtypes. The present study aimed to investigate whether the occurrence of PM, PD and MAE were associated with one another.
Methods: This is a nationwide register-based, historical prospective cohort study. Data was obtained from the Danish Psychiatric Central Research Register. Subjects were defined as all individuals assigned with an ICD-10 diagnosis of bipolar disorder between January 1st 1994 and December 31st 2010. Potential associations among psychotic and mixed affective episodes were tested by means of logistic regression.
Results: We identified 14,529 individuals with bipolar disorder with lifetime incidences of PM, PD and MAE of 19%, 15% and 17% respectively. We detected significant associations between PM and MAE (Adjusted Odds Ratio (AOR)=1.26, p=0.003), PD and MAE (AOR=1.24, p=0.001), and PM and PD (AOR=1.28, p=0.005).
Limitations: Diagnoses were assigned as part of routine clinical practice.
Conclusions: According to this register-based study, PD, PM and MAE are all associated with one another. This knowledge should be taken into consideration by clinicians when monitoring patients with bipolar disorder and by nosologists when defining the criteria and potential subtypes for mixed affective episodes for the upcoming DSM-5 and ICD-11.
Copyright © 2012 Elsevier B.V. All rights reserved.